A Global Positioning System (GPS) is a space based global navigation satellite system that utilizes a network of geo-synchronous satellites which can be utilized by a GPS receiver to determine its location. Many telematics systems incorporate a Global Positioning System (GPS) receiver, which can be used to obtain the location of a vehicle at a certain measured time. By comparing the location of a vehicle at a plurality of measured times, the speed of the vehicle can be determined. GPS receivers can also determine speed by measuring the Doppler shift in the received satellite signals. The acceleration of the vehicle can be determined as the change in speed divided by the time between the measurements. A GPS receiver's ability to determine acceleration can be limited due to the dependence of the measurement upon factors such as reception and satellite availability. In addition to location information, a GPS receiver can also be configured to provide time data.
An accelerometer is a device that measures acceleration associated with the weight experienced by a test mass in the frame of reference of the accelerometer device. The acceleration measured by an accelerometer is typically a weight per unit of test mass, or g-force.
Telematics is the integrated use of telecommunications and informatics. Telematics units are installed in vehicles to provide a variety of telematics functionality in the vehicle. This functionality includes, but is not limited to, emergency warning systems, navigation functionality, safety warnings, and automated driving assistance. Telematics units are also capable of recording data related to the operation of the vehicle and providing that information for analysis, whether in real-time or during a time when the vehicle is being serviced. This information can be used in a variety of applications, such as fleet tracking, shipment tracking, insurance calculations, and in vehicle management and service.